The need to increase magnetic recording densities while maintaining acceptable stability is an on-going challenge for magnetic disk drive designers. Thin film magnetic recording mediums with relatively high magnetic anisotropy and high coercivity provide greater thermal stability, but these parameters are constrained by the strength of the magnetic field that can be generated by the thin film write head to reverse the magnetic orientation of the domains.
One method that allows the more stable magnetic materials to be written is thermally-assisted magnetic recording (TAMR). In TAMR, the magnetic material in the target area is briefly heated to lower both coercivity and anisotropy to allow a lower magnetic field to write the domain. Instantaneous heating aids in writing narrow data tracks on the media. One way to generate the required heat is by integrating a laser diode into the slider along with the read and write heads. Prior systems use DC biasing for the laser signal. There is a need for designs that efficiently use laser-pulses instead of DC biasing to improve the TAMR performance with respect to thermal gradient of the near field transducer and for laser stability. This allows better thermal management of the write head, better synchronization between write data and laser heating cycle as well as prevention of mode hopping in laser diode.